Dear @TAM Wing Hong,
Thank you for posting your question in the Microsoft Q&A forum.
Since cancel subscription and refund request things need action/approval from Billing team, so you have to raise the support ticket to Billing Team under correct/affected tenant. For that reason, the priority is that you have to get access back to your affected tenant.
Since you are using business account, are you the only admin or there are other admins in your company?
Related to Authenticator app, since you are using business account provided by your company, here are some options I recommend you look through:
Option 1: If you are user or have other admins in your company, to regain access to your account, I recommend you contact your IT admin/Global admin to raise a request for resetting your authentication method in the Entra admin center.
Admin can revoke MFA sessions and require re-registration in Microsoft Entra admin center. For step-by-step details, refer to the official Microsoft documentation: Manage authentication methods for Microsoft Entra multifactor authentication - Microsoft Entra ID | Microsoft Learn
Option 2: Contact Microsoft Data Protection Support by Phone
Since you are the only administrator and are locked out, the most direct method is to call Microsoft's support line to raise a request for resetting your authentication method. For a full list of regional numbers, you can also visit this official page: Customer service phone numbers - Microsoft Support. The support team will assist you as soon as possible. For reference: Get support | Microsoft Docs
Here are some tips and an example of a prompt to help you navigate the IVR more effectively:
In some countries, it is an automated conversation like: First, when you call the hotline, it will be asked as follows:
IVR: What kind of problem are you concerned about?
You: Authenticator.
IVR: What kind of product do you use?
You: Office 365 for business.
IVR confirmation: education or company account?
You: For companies
IVR: Are you an administrator?
You: Yes.
IVR: Do you have the other administrator in your organization?
You: No.
IVR: Do you need a... Service request?
You: Yes
This process should connect you with a live agent who will create a service request with the Data Protection team. They will then contact you to help you regain access.
Option 3: Create a Temporary Account (Trial Tenant) to Submit a Support Ticket
If you have difficulty reaching an agent by phone, there is a reliable workaround. This involves creating a new, temporary Microsoft 365 account to contact the support team online.
- Sign up for a new Microsoft 365 Business trial using this link: Compare All Microsoft 365 Plans. You will need to use a different, personal email address to register.
- Once the trial account is created, log in to its Admin Center.
- From the Admin Center, open a new Service Request. For reference: Get support | Microsoft Docs
- In the ticket description, explain that you are locked out of your primary tenant (your.onmicrosoft.com) and that you need to speak with the Data Protection team to regain access. Provide your locked account's details and a good contact number for them to reach you.
Important: Please remember to cancel the trial subscription after your original account issue is resolved to avoid any future charges.
I am confident that the Data Protection team can resolve this for you. Please try the phone option first, as it is the most direct path. Let me know if you have any questions about these steps.
Note: Please understand that as a forum moderator, my role is to provide general guidance and troubleshooting support. I don’t have access to internal systems or backend tools, and I appreciate your understanding of these limits.
I hope the information shared helps point you in the right direction. Please try the steps above and let me know if they work. If not, we can continue working together to narrow this down.
The first response may not always resolve the issue right away, but with your help and more details, we can work toward a solution.
Thank you for your patience and understanding. I'm looking forward for your reply.
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